This invention relates to electrophotographic photosensitive members and methods for maufacturing the same, more particularly relates to an application of microwave enhanced CVD.
From the state of the art it is known to utilize plasma enhanced CVD (glow discharge CVD) in which process gas is excited by high frequency or direct electric field, for fabricating thin film on a printing drum. This prior art method is advantageous in that deposition can be performed at a low temperature in comparison with conventional thermal CVD. Particularly, in deposition of such as amorphous silicon semiconductor, it is possible to add hydrogen or a halogen in the semiconductor to neutralize recombination centers according to this method.
The deposition speed of the glow discharge CVD, however, is very slow, 1 to 3 21 for example, so that it is demanded to increase the speed by a factor to 10 to 500 for commertializing the method. In addition, the method tends to give rise to coming off and cracks of a film deposited with only about one micron in thickness when having used for a time or having underwent temperature charges. Also degradation due to light irradiation has been observed on a film whose thickness is more than about 0.5 micron. When the thickness further increases during deposition, localization of electrical field takes place on the deposition surface and thereby the deposition is partially enhanced at the localized position of the surface to a thickness of 2 to 10 microns resulting in an uneven surface. Because of this, an improved method has been demanded to form an even layer at a low temperature lower than 300.degree. C. with 2 to 10 microns in thickness.